configure.ac: Report if built with XCB-XKB or not
configure.ac: Report if built with XCB-XKB or not

Signed-off-by: Jonas Ådahl <67dcd8a17e758192e0cbb577ce1d62cc7da6cf49@gmail.com>

Fantu/compositor-spice,xorgy/weston,Gnurou/weston,giucam/weston,sir-murray/weston,jonnylamb/weston,xorgy/weston,eyolfson/weston,Gnurou/weston,Fantu/compositor-spice,giucam/weston,udoprog/weston,Fantu/compositor-spice,mchalupa/weston,Tarnyko/weston-xdg_surface_present,Tarnyko/weston-xdg_surface_present,mchalupa/weston,krezovic/weston,kwm81/weston,krezovic/weston,udoprog/weston,kwm81/weston,jonnylamb/weston,eyolfson/weston,sir-murray/weston